This invention relates to a liquid propellant gun and more specifically to an injection system for a propellant gun and most particularly to a concentric valve arrangement for fuel and oxidizer injection characterized by zero ullage, elimination of back pressure in the injector and automatic valve operation.
Known prior art liquid propellant guns do not have zero ullage. When the fuel does not completely fill the gun chamber, ignition and interior ballistics become less predictable because ullage promotes erratic burning and large pressure excursions resulting ultimately in gun damage. In some prior art devices the injectors develop a swirl in the fluid column which tends to concentrate gas bubbles at the center of the fluid column further contributing to erratic burning of the propellant.
Some previous designs have used conventional carburetion to produce a fuel air mixture as the propellant. The carburetion method requires a much larger volume of propellant for a given amount of energy in comparison to the liquid fuel and oxidizer usable with the present invention. Furthermore, the carburetion system requires a source of air which would not be readily available if the gun were in an application in the upper atmosphere or further out in space.
Other prior art weapons have suffered from other drawbacks such as complex linkages to control the propellant valve, breech pressure acting on valve components and obturating seals being damaged by passing over valve parts or inlet ports.